1. Field of the Invention
The present invention relates generally to the field of environmental protection mechanisms. More specifically the present invention relates to a secondary containment cap apparatus for incorporating into the turret structure of a hazardous fluid primary container to provide secondary containment against fluid leakage into the natural environment from liquid and vapor passing container valves. Such primary containers may be free-standing or vehicle-mounted. The hazardous fluid within the primary container is a gas or a liquid or a combination of the two, which is poisonous, caustic or otherwise health threatening, such as chlorine and sulphur dioxide liquified gas.
The turret of each type of primary container includes a turret opening in the primary container wall with a tubular turret opening perimeter wall extending outwardly from the container wall and having a perimeter wall rim, and the secondary containment cap apparatus fits and is sealingly secured to the turret opening perimeter wall with high tension bolts mounting through existing bolt holes, such as in a turret mounting flange protruding laterally from the perimeter wall rim, and retains any gas leaking from the liquid and vapor valves into the interior of the cap apparatus to prevent escape into the environment. The cap apparatus preferably includes a valve mounting plate mounted sealingly across the perimeter wall rim, the valves extending through and being sealingly secured within the valve mounting plate, and a containment cap which, in its essential form, includes a substantially cup- or bubble-shaped cap wall defining a concave cap interior and a cap abutment port surrounded by a cap port rim fitting sealingly against the valve mounting plate to enclose the valves, vapor release means for controlled release of gas contained within the cap wall into secure containers or scrubber means, and attachment means for securing the valve mounting plate to the primary container with the valve mounting plate sealingly fitted against the turret opening perimeter wall rim. The cap wall preferably is a wide cylindrical tube with an open cap side wall remote end and a cap wall mounted end welded onto the valve mounting plate, and a spring-loaded hinged hatch is sealingly secured onto the open cap side wall remote end.
2. Description of the Prior Art
In recent years there have been numerous instances of chlorine gas released from bulk storage tanks, railroad tanker cars, tanker trucks and barges. Many communities have adopted new regulations requiring containment of toxic gas releases, such as Article 80 of the Uniform Fire Code and the Toxic Gas Ordinance. A problem with existing chlorine tanks and valves has been that they have no secondary containment, so that a release of chlorine from the tank or tank valving causes an instant and life threatening discharge of chlorine gas. Valves within valve mounting turrets of tank railroad cars, trucks and barges, and bulk storage tanks are particularly prone to hazardous leakage. Yet valve covers provided on existing, prior art valve mounting turrets are not pressure covers and are not configured, are not of sufficient gauge and are not otherwise designed to provide secondary containment around the valves in the event of a hazardous gas leak. Furthermore, these prior covers do not include release valves for metered release of any gas which might enter the cover and do not provide fail-safe shut down of release in the event of unauthorized movement, earthquakes or detection of other gas leakage.
There have in recent years been devices intended for containing and scrubbing chlorine gas leaking from cylinders, and vehicles. These devices traditionally have included a hood or building structure placed around the leaking cylinder or vehicle and a scrubber apparatus for gradually removing the chlorine gas from the air within the hood or building. A problem with these devices has been that the containment buildings and hoods are not capable of withstanding the pressure and corrosive nature of suddenly released quantities of chlorine gas. Being largely intended for ton and 150 pound chlorine gas cylinders, such technology is wholly ineffective and unsuited for the large, perhaps 90 ton tanks found on chlorine transport vehicles and the sometimes massive stationary bulk storage tanks.
A solution to the problem of safely draining leaking chlorine cylinders has been found and is disclosed in U.S. Pat. Nos. 5,607,384 and 5,819,787, issued on Mar. 4, 1997 and Dec. 13, 1998, respectively, to the present applicant. These patents disclose sealing leaking chlorine cylinders in a pressure-withstanding secondary containment vessel, resembling on some ways an iron lung. Gas is slowly released through a valve in the secondary containment vessel to a scrubber apparatus of conventional design at a suitable metered rate. In the event of a catastrophic rupture and sudden release of gas from the cylinder, the secondary containment vessel entirely and safely contains the released gas, which once again is discharged at a suitable rate to a scrubber apparatus or put into process. A limitation to this approach is that it is impractical to build secondary containment vessels of the type disclosed in these patents which are large enough to receive bulk storage tanks and chlorine transport vehicles, and it is impractical to attempt to move such a leaking storage tank or tanker vehicle to the site of such a massive vessel or to move the massive vessel to and around the tanker vehicle. Additionally, there are so many sizes and shapes of tanks and transport vehicles that no single size and shape of receiving vessel could be suitable for all of them. Further a hood or alternative method may not fully comply with fire codes.
It is thus an object of the present invention to provide a secondary containment cap apparatus for enclosing release ports and liquid and vapor passing valves mounted in the release ports within a turret of a primary container such as a hazardous fluid containment bulk storage or vehicle tank, the containment cap apparatus being manufactured separately from the primary container, so that any fluid subsequently leaking from the valves or release ports of the primary container is contained within the containment cap apparatus and can be drained off through a port and valve in the cap apparatus into cylinders or other receiving means in the conventional way for ordinary usage, and in which the secondary containment cap apparatus is capable of withstanding the maximum hazardous fluid pressure which can be exerted by the quantity of retained hazardous fluid so that the natural environment is safely shielded from the hazardous fluid. As a result, there is no need to go to the considerable expense of scrubbing the leaking fluid and no need to expose anyone to the dangers involved in such a clean-up operation.
It is more specifically an object of the present invention to provide such a cap apparatus which encloses the gas release ports and valves of the primary container in a limited secondary containment structure which is less expensive than providing secondary containment of the entire primary container.
It is a further object of the present invention to provide such a cap apparatus which can be permanently or removably secured with high tension bolts fitted into existing bolt passing holes or notches manufactured as an original structure of the primary container, and which provides safe containment during primary container transport and operation at the job site.
It is an additional object of the present invention to provide such a cap apparatus in which the primary container gas release port is fitted with a remote operating container valve which is operable from outside the containment cap apparatus so that the valve can be operated without entering the containment cap apparatus and no personnel are therefore exposed to leaking hazardous fluid.
It is a further object of the present invention to provide such a cap apparatus which is equipped with a hazardous fluid pressure/vacuum gauge and detection devices for indicating leaks and optionally for indicating completed draining of hazardous fluid from the cap structure.
It is still another object of the present invention to provide such a cap apparatus which complies with Article 80 of the Uniform Fire Code and with the California Toxic Gas Ordinance.
It is yet another object of the present invention to provide such a cap apparatus which has fail-safe valves connected to its release fittings, the fail-safe valves being electrically wired to a motion and impact sensor, and connected to a hazardous fluid leakage sensor, which rapidly closes the fail-safe valve in the event of an earthquake, an attempt to move the primary container without authorization, or a hazardous fluid leak, and which can be easily adapted to existing tank design for low cost installation.
It is finally an object of the present invention to provide such a cap apparatus which is easy to use and is highly reliable, simple in design, safe, virtually maintenance free, compact, and can be manufactured at an expense relatively comparable to or lower than that of existing containment systems.
The present invention accomplishes the above-stated objectives, as well as others, as may be determined by a fair reading and interpretation of the entire specification.
A secondary containment cap apparatus is provided for incorporating into a turret of a primary container for containing a hazardous fluid, the primary container having a primary container wall with a primary container turret opening having a turret opening perimeter wall and a perimeter wall rim, the secondary containment cap apparatus including a valve mounting plate extending over and covering the turret opening in sealing relation with the perimeter wall, the valve mounting plate having at least one valve port fitted with a fluid passing container valve; a containment cap including a cap wall shaped to define a concave cap interior and a cap abutment port, the cap abutment port having a cap abutment port rim, the containment cap being secured onto the valve mounting plate so that the container cap covers and encloses the fluid passing container valve, the cap abutment port rim being retained in sealing relation with the valve mounting plate to provide secondary containment of the fluid passing container valve; and cap attachment structure securing the valve mounting plate to the perimeter wall.
The apparatus preferably additionally includes a mechanism for controlled release of the fluid through the cap wall. The cap wall preferably includes an outer access port and an outer access hatch removably and sealingly covering the outer access port. The outer access hatch preferably is secured to the outer access port with a hatch hinge. The apparatus preferably additionally includes a hatch spring biasing the outer access hatch into a closed position on the outer access port. The apparatus preferably additionally includes a hatch bolting structure for releasibly bolting the outer access hatch onto the cap wall in a closed position on the outer access port. The cap attachment mechanism preferably includes fasteners interconnecting the perimeter wall rim and the valve mounting plate. The apparatus preferably additionally includes a gasket compressed and creating a seal between the valve mounting plate and the perimeter wall rim.
The perimeter wall rim preferably includes a turret mounting flange and the cap attachment structure preferably includes bolt passing flange openings in the turret mounting flange and bolt passing plate openings in the valve mounting plate registering with the bolt passing flange openings and includes several bolts, each the bolt extending through one of the bolt passing flange openings and through a corresponding and registering bolt passing plate opening, thereby securing the turret mounting flange and the valve mounting plate together.
The at least one fluid passing container valve preferably includes at least one liquid passing valve and at least one vapor passing valve. The at least one fluid passing container valve preferably includes a valve intake orifice in fluid communication with the at least one fluid release port and preferably includes a valve discharge orifice, the apparatus additionally including a lateral valve pipe extending through the cap wall and having a lateral pipe valve end connected to the at least one fluid passing container valve and having a lateral pipe remote end extending outside the container cap, so that fluid passing through the at least one fluid passing container valve can be released through the lateral pipe remote end outside the containment cap.
The apparatus preferably additionally includes a fail-safe valve secured to and in fluid communication with the lateral pipe remote end. The apparatus preferably still additionally includes a motion detector including a signalling mechanism in communication with the fail-safe valve for automatically closing the fail-safe valve upon detection of primary container, and an external hazardous fluid detector including a signalling mechanism in communication with the fail-safe valve for automatically closing the fail-safe valve upon detection of hazardous fluid outside the primary container, and an alarm sound generator connected to the motion detector signaling mechanism for automatically initiating the generation of an alarm sound upon detection of primary container movement.
The apparatus preferably still additionally includes an alarm sound generator connected to the external hazardous fluid detector signaling mechanism for automatically initiating the generation of an alarm sound upon detection of hazardous fluid outside the primary container. The apparatus optionally additionally includes a second internal hazardous fluid detector located between the primary container wall and the cap wall for detecting leakage of hazardous fluid from the primary container.